We evolved alongside parasites that weaken us,
and recently in human history we were able to get rid of those parasites. What would happen? Our bodies would overcompensate, just like the “floating arms” experiment.

If parasites weakened the immune system, then human bodies would adapt by making the immune system more aggressive. Removing the parasites would lead to human immune systems increasingly overreacting to things. There are some people who infect themselves with parasites to treat allergies and immune disorders.

If parasites increased our aggressiveness (as toxoplasma gondii is hypothesized to do), then humans would adapt by lowering aggressivness. Removing the parasites would lead to more the human race becoming more passive.

If parasites weakened our mental abilities, then humans would adapt by making extra-powerful brains. Removing the parasites would lead to more intelligent humans.

Is it possible that human brains are far more powerful than they need to be for survival in the wild because parasite evolution forced them to be that way?